ON LIQUOR B1SMUTUI ET AMMONIAS CITRATIS. 
469 
of his preparations a trace of copper, but the liquor that contained it was pre¬ 
pared from metal which had not been fused with nitre sufficiently.” Nowhere 
we are at complete issue. Mr. Wood says, that fusing bismuth twice with one- 
tenth of its weight of nitre for a quarter of an hour, with constant stirring, 
will free it from contaminating copper. I say it will not. He does not, how¬ 
ever, give us the detail of any experiments in support of his views ; indeed, I 
scarcely think he can have tried one, for I will presently detail an experiment, 
the results of which are diametrically opposed to his assertions. In the mean¬ 
time I have sought in vain for any authority for this doctrine ; nor can I see 
upon what grounds the chemist would expect such a result. The very process 
is used in the arts for purifying copper itself. The respective oxidizabilities of 
the two metals are very nearly equal; indeed, at high temperatures, bismuth 
appears to be capable of displacing copper from its solutions. Any oxidizing 
process, therefore, applied to the mixed metals would be likely to attack them 
both. And such 1 find experimentally to be the case. 
I had a sample of bismuth (A) which I tested for copper thus :—I dissolved 
10 grains in a little diluted nitric acid, and added ammonia in excess. After 
the subsidence of the bismuth oxide, a deep blue solution appeared on the top. 
This was filtered off, evaporated nearly to dryness, slightly acidulated with 
acetic acid, and touched with ferrocyanide of potassium. A rich brown preci¬ 
pitate was at once produced. The presence of copper was by these means con¬ 
sidered proved. 1000 grains of this coppery bismuth (A) were then fused with 
100 grains of nitre for fifteen minutes, and constantly stirred. The slag was 
separated by boiling in water, aud the button of metal again fused with 100 
grains of nitre for fifteen minutes, and stirred. The metal (B), upon being 
again separated by boiling from the slag, was found to have lost 73 grains. 
10 grains of B were then tested for copper, as in the previous experiment with 
A, and were found to yield abuudaut evidence of copper. 
But one step more was taken. The metal B was then a third time fused with 
nitre, and kept stirred, with additions of fresh salt for an hour and a half. The 
slag was once more separated, and the metal (C) was now found to have lost 
170 grains. 10 grains of C, when treated as A and B, still yielded abundant 
evidence of copper. These fusions were conducted in a glazed porcelain crucible, 
so as to avoid the loss of a particle of the fused metal by absorption or mecha¬ 
nical adhesion. 
These considerations and experiments justify me, I think, in asserting that 
the Pharmacopoeia process for the purification of bismuth does not free it from 
copper; and as Mr. Wood admits it to be u the most abundant impurity in 
commercial bismuth,” the second commercial statement of my advertisement is 
also shown to be scientifically correct. 
We also see that the chemical activity of the nitre is exercised upon the bis¬ 
muth itself, resulting in a loss of that metal to an extent, varying with the 
duration of the process, of from 7 to 17 per cent. I think my assumption that 
manufacturers will shrink from adopting this so-called purification, is by no 
means extravagant. 
The remaining subject of difference between us, namely, about the arsenic 
and antimony, deserves further investigation, and I am sorry Mr. Wood did not 
grant us some details, by which we might feel assured that the sample he ope¬ 
rated upon was really arsenicated before the experiment, and really pure after¬ 
wards, so that our exact knowledge upon this point might have been advanced. 
There is no doubt fusion with nitre will remove the greater proportion of the 
arsenic from bismuth, but whether the whole will be removed depends, probably, 
upon the quantities operated upon. I have been too much occupied lately to 
repeat my old experiments upon this point; I must, therefore, leave this part of 
the subject to a future occasion. In the meantime I would refer all interested 
